This invention relates to a camera mount which is particularly useful in three-dimensional (3-D) photography for controlling the so-called "interocular" spacing and convergence distance between the respective optical axes of a pair of 3-D cameras for the purpose of producing different three-dimensional effects.
The production of three-dimensional photographs, both cine and still, is well known in the art and usually involves the use of two cameras which record the same scene from different perspectives. Typically, the nominal effective lateral displacement between the respective optical axes of the cameras, known as the interocular spacing, is approximately equal to the average spacing between the eyes of a viewer (i.e. about 2.5 inches). This spacing would produce the same 3-D effect as that perceived by a viewer who viewed the scene from the camera location. A greater or lesser interocular spacing is sometimes desirable to produce greater or lesser depth. Hence, conventional 3-D camera systems commonly include some means for adjusting the position of one camera relative to the other to vary the interocular spacing over a continuous range from zero to about 4 or 5 inches.
Aside from interocular spacing adjustment, 3-D effects can also be controlled by varying the convergence distance at which the optical axes of the respective 3-D cameras intersect. When 3-D images are projected for viewing, such convergence distance determines the distance at which objects within the scene appear to be located relative to the projection screen. When the convergence angle is such that the camera axes intersect at, say, thirty feet in front of the cameras, objects in the foreground and background will appear to a viewer to be positioned in front of and behind the screen, respectively. Special well known 3-D effects can be achieved in 3-D motion picture photography by varying the convergence distance during filming, and conventional 3-D camera systems commonly include means for adjusting the position of one camera relative to the other to vary such distance over a continuous range between infinity and about four feet.
An apparatus for precisely moving one 3-D camera relative to the other to produce independent interocular spacing and/or convergene distance adjustments is disclosed in my co-pending U.S. patent application, Ser. No. 535,991, filed on Sept. 26, 1983 and assigned to Walt Disney Productions, now U.S. Pat. No. 4,557,570 . Such apparatus comprises a four-bar linkage which includes a pair of relatively long side links pivotally connected between a pair of comparatively shorter end links. One of the end links is fixed to a frame, and the other end link is secured to a movable camera. Swinging movement of the side links alters the interocular spacing between the movable camera and a fixed camera, and shifting the relative positions of the pivot points of the side links alters the convergence distance. While such apparatus is quite effective in providing independent interocular spacing and convergence distance adjustments the linkage assembly is somewhat complex in construction and bulky in physical size, the latter disadvantage limiting its usage, and the former its cost and reliability.